[llvm] fb47115 - [llvm] boilerplate for new callbrprepare codegen IR pass
Nick Desaulniers via llvm-commits
llvm-commits at lists.llvm.org
Thu Feb 16 18:03:55 PST 2023
Author: Nick Desaulniers
Date: 2023-02-16T17:58:33-08:00
New Revision: fb471158aa0da2690beb3be3af2618af2f5bf4df
URL: https://github.com/llvm/llvm-project/commit/fb471158aa0da2690beb3be3af2618af2f5bf4df
DIFF: https://github.com/llvm/llvm-project/commit/fb471158aa0da2690beb3be3af2618af2f5bf4df.diff
LOG: [llvm] boilerplate for new callbrprepare codegen IR pass
Because this pass is to be a codegen pass, it must use the legacy pass
manager.
Link: https://discourse.llvm.org/t/rfc-syncing-asm-goto-with-outputs-with-gcc/65453/8
Reviewed By: aeubanks, void
Differential Revision: https://reviews.llvm.org/D139861
Added:
llvm/lib/CodeGen/CallBrPrepare.cpp
llvm/test/CodeGen/AArch64/callbr-prepare.ll
Modified:
llvm/include/llvm/CodeGen/CodeGenPassBuilder.h
llvm/include/llvm/CodeGen/MachinePassRegistry.def
llvm/include/llvm/CodeGen/Passes.h
llvm/include/llvm/InitializePasses.h
llvm/lib/CodeGen/CMakeLists.txt
llvm/lib/CodeGen/CodeGen.cpp
llvm/lib/CodeGen/TargetPassConfig.cpp
llvm/tools/opt/opt.cpp
llvm/utils/gn/secondary/llvm/lib/CodeGen/BUILD.gn
Removed:
################################################################################
diff --git a/llvm/include/llvm/CodeGen/CodeGenPassBuilder.h b/llvm/include/llvm/CodeGen/CodeGenPassBuilder.h
index 9ac51ed9f6fad..d9c7bf626dc90 100644
--- a/llvm/include/llvm/CodeGen/CodeGenPassBuilder.h
+++ b/llvm/include/llvm/CodeGen/CodeGenPassBuilder.h
@@ -714,6 +714,7 @@ template <typename Derived>
void CodeGenPassBuilder<Derived>::addISelPrepare(AddIRPass &addPass) const {
derived().addPreISel(addPass);
+ // addPass(CallBrPrepare()); // TODO(ndesaulniers): impl pass
// Add both the safe stack and the stack protection passes: each of them will
// only protect functions that have corresponding attributes.
addPass(SafeStackPass());
diff --git a/llvm/include/llvm/CodeGen/MachinePassRegistry.def b/llvm/include/llvm/CodeGen/MachinePassRegistry.def
index 8efd1d2e95e93..a29269644ea1d 100644
--- a/llvm/include/llvm/CodeGen/MachinePassRegistry.def
+++ b/llvm/include/llvm/CodeGen/MachinePassRegistry.def
@@ -123,6 +123,7 @@ DUMMY_FUNCTION_PASS("cfguard-dispatch", CFGuardDispatchPass, ())
DUMMY_FUNCTION_PASS("cfguard-check", CFGuardCheckPass, ())
DUMMY_FUNCTION_PASS("gc-info-printer", GCInfoPrinterPass, ())
DUMMY_FUNCTION_PASS("select-optimize", SelectOptimizePass, ())
+DUMMY_FUNCTION_PASS("callbrprepare", CallBrPrepare, ())
#undef DUMMY_FUNCTION_PASS
#ifndef DUMMY_MODULE_PASS
diff --git a/llvm/include/llvm/CodeGen/Passes.h b/llvm/include/llvm/CodeGen/Passes.h
index 530369fb073e5..3ee3e505da716 100644
--- a/llvm/include/llvm/CodeGen/Passes.h
+++ b/llvm/include/llvm/CodeGen/Passes.h
@@ -597,6 +597,8 @@ namespace llvm {
/// This pass converts conditional moves to conditional jumps when profitable.
FunctionPass *createSelectOptimizePass();
+
+ FunctionPass *createCallBrPass();
} // End llvm namespace
#endif
diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
index 5c531ea89cc62..9d3adbf839077 100644
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h
@@ -83,6 +83,7 @@ void initializeCFGuardLongjmpPass(PassRegistry&);
void initializeCFGViewerLegacyPassPass(PassRegistry&);
void initializeCFIFixupPass(PassRegistry&);
void initializeCFIInstrInserterPass(PassRegistry&);
+void initializeCallBrPreparePass(PassRegistry &);
void initializeCallGraphDOTPrinterPass(PassRegistry&);
void initializeCallGraphPrinterLegacyPassPass(PassRegistry&);
void initializeCallGraphViewerPass(PassRegistry&);
diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index cac16e59a51d1..7a3a82b10c5c8 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -35,6 +35,7 @@ add_llvm_component_library(LLVMCodeGen
BasicBlockSections.cpp
BasicBlockSectionsProfileReader.cpp
CalcSpillWeights.cpp
+ CallBrPrepare.cpp
CallingConvLower.cpp
CFGuardLongjmp.cpp
CFIFixup.cpp
diff --git a/llvm/lib/CodeGen/CallBrPrepare.cpp b/llvm/lib/CodeGen/CallBrPrepare.cpp
new file mode 100644
index 0000000000000..4bec56c20eb2c
--- /dev/null
+++ b/llvm/lib/CodeGen/CallBrPrepare.cpp
@@ -0,0 +1,75 @@
+//===-- CallBrPrepare - Prepare callbr for code generation ----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass lowers callbrs in LLVM IR in order to to assist SelectionDAG's
+// codegen.
+//
+// In particular, this pass assists in inserting register copies for the output
+// values of a callbr along the edges leading to the indirect target blocks.
+// Though the output SSA value is defined by the callbr instruction itself in
+// the IR representation, the value cannot be copied to the appropriate virtual
+// registers prior to jumping to an indirect label, since the jump occurs
+// within the user-provided assembly blob.
+//
+// Instead, those copies must occur separately at the beginning of each
+// indirect target. That requires that we create a separate SSA definition in
+// each of them (via llvm.callbr.landingpad), and may require splitting
+// critical edges so we have a location to place the intrinsic. Finally, we
+// remap users of the original callbr output SSA value to instead point to the
+// appropriate llvm.callbr.landingpad value.
+//
+// Ideally, this could be done inside SelectionDAG, or in the
+// MachineInstruction representation, without the use of an IR-level intrinsic.
+// But, within the current framework, it’s simpler to implement as an IR pass.
+// (If support for callbr in GlobalISel is implemented, it’s worth considering
+// whether this is still required.)
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Pass.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "callbrprepare"
+
+namespace {
+
+class CallBrPrepare : public FunctionPass {
+public:
+ CallBrPrepare() : FunctionPass(ID) {}
+ static char ID;
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+ bool runOnFunction(Function &Fn) override;
+};
+
+} // end anonymous namespace
+
+char CallBrPrepare::ID = 0;
+INITIALIZE_PASS(CallBrPrepare, DEBUG_TYPE, "Prepare callbr", false, false)
+
+FunctionPass *llvm::createCallBrPass() { return new CallBrPrepare(); }
+
+void CallBrPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+}
+
+bool CallBrPrepare::runOnFunction(Function &Fn) {
+ for (BasicBlock &BB : Fn) {
+ auto *CBR = dyn_cast<CallBrInst>(BB.getTerminator());
+ if (!CBR)
+ continue;
+ // TODO: something interesting.
+ // https://discourse.llvm.org/t/rfc-syncing-asm-goto-with-outputs-with-gcc/65453/8
+ }
+ return false;
+}
diff --git a/llvm/lib/CodeGen/CodeGen.cpp b/llvm/lib/CodeGen/CodeGen.cpp
index 0803c2cf66b28..6a3feb79e822d 100644
--- a/llvm/lib/CodeGen/CodeGen.cpp
+++ b/llvm/lib/CodeGen/CodeGen.cpp
@@ -24,6 +24,7 @@ void llvm::initializeCodeGen(PassRegistry &Registry) {
initializeBasicBlockSectionsPass(Registry);
initializeBranchFolderPassPass(Registry);
initializeBranchRelaxationPass(Registry);
+ initializeCallBrPreparePass(Registry);
initializeCFGuardLongjmpPass(Registry);
initializeCFIFixupPass(Registry);
initializeCFIInstrInserterPass(Registry);
diff --git a/llvm/lib/CodeGen/TargetPassConfig.cpp b/llvm/lib/CodeGen/TargetPassConfig.cpp
index a047e66dcc014..2e697dda1ccde 100644
--- a/llvm/lib/CodeGen/TargetPassConfig.cpp
+++ b/llvm/lib/CodeGen/TargetPassConfig.cpp
@@ -978,6 +978,8 @@ void TargetPassConfig::addISelPrepare() {
if (requiresCodeGenSCCOrder())
addPass(new DummyCGSCCPass);
+ // addPass(createCallBrPass()); // TODO(ndesaulniers): impl pass
+
// Add both the safe stack and the stack protection passes: each of them will
// only protect functions that have corresponding attributes.
addPass(createSafeStackPass());
diff --git a/llvm/test/CodeGen/AArch64/callbr-prepare.ll b/llvm/test/CodeGen/AArch64/callbr-prepare.ll
new file mode 100644
index 0000000000000..3e83afe0175f8
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/callbr-prepare.ll
@@ -0,0 +1,30 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt %s -callbrprepare -S -o - | FileCheck %s
+
+; TODO: update this test to split critical edges.
+define i32 @test0() {
+; CHECK-LABEL: @test0(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[OUT:%.*]] = callbr i32 asm "# $0", "=r,!i"()
+; CHECK-NEXT: to label [[DIRECT:%.*]] [label %indirect]
+; CHECK: direct:
+; CHECK-NEXT: [[OUT2:%.*]] = callbr i32 asm "# $0", "=r,!i"()
+; CHECK-NEXT: to label [[DIRECT2:%.*]] [label %indirect]
+; CHECK: direct2:
+; CHECK-NEXT: ret i32 0
+; CHECK: indirect:
+; CHECK-NEXT: [[OUT3:%.*]] = phi i32 [ [[OUT]], [[ENTRY:%.*]] ], [ [[OUT2]], [[DIRECT]] ]
+; CHECK-NEXT: ret i32 [[OUT3]]
+;
+entry:
+ %out = callbr i32 asm "# $0", "=r,!i"()
+ to label %direct [label %indirect]
+direct:
+ %out2 = callbr i32 asm "# $0", "=r,!i"()
+ to label %direct2 [label %indirect]
+direct2:
+ ret i32 0
+indirect:
+ %out3 = phi i32 [%out, %entry], [%out2, %direct]
+ ret i32 %out3
+}
diff --git a/llvm/tools/opt/opt.cpp b/llvm/tools/opt/opt.cpp
index ec338c8574447..1b07bbe094163 100644
--- a/llvm/tools/opt/opt.cpp
+++ b/llvm/tools/opt/opt.cpp
@@ -392,7 +392,8 @@ static bool shouldPinPassToLegacyPM(StringRef Pass) {
"expand-large-div-rem",
"structurizecfg",
"fix-irreducible",
- "expand-large-fp-convert"
+ "expand-large-fp-convert",
+ "callbrprepare",
};
for (const auto &P : PassNamePrefix)
if (Pass.startswith(P))
@@ -444,6 +445,7 @@ int main(int argc, char **argv) {
initializeExpandMemCmpPassPass(Registry);
initializeScalarizeMaskedMemIntrinLegacyPassPass(Registry);
initializeSelectOptimizePass(Registry);
+ initializeCallBrPreparePass(Registry);
initializeCodeGenPreparePass(Registry);
initializeAtomicExpandPass(Registry);
initializeRewriteSymbolsLegacyPassPass(Registry);
diff --git a/llvm/utils/gn/secondary/llvm/lib/CodeGen/BUILD.gn b/llvm/utils/gn/secondary/llvm/lib/CodeGen/BUILD.gn
index 513c635a29b5b..bc37796e1a2d8 100644
--- a/llvm/utils/gn/secondary/llvm/lib/CodeGen/BUILD.gn
+++ b/llvm/utils/gn/secondary/llvm/lib/CodeGen/BUILD.gn
@@ -34,6 +34,7 @@ static_library("CodeGen") {
"CFIFixup.cpp",
"CFIInstrInserter.cpp",
"CalcSpillWeights.cpp",
+ "CallBrPrepare.cpp",
"CallingConvLower.cpp",
"CodeGen.cpp",
"CodeGenCommonISel.cpp",
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